Just recently the computer started refusing to boot, the computer will power up, make the chime, show the gray screen but won't go past it, won't even show an apple logo.

I believe it is freezing shortly after powering up, when i hold down the option key the mouse does show up but its frozen and never shows bootable discs.

There are rare occasions that it will not freeze, in which case i am able to get it to attempt to load the os off the hard drive, or load the restore disc that came with the computer, but during the process the prohibitory sign appears (the crossed out circle).

I tried removing the hard drive and booting it, but the issue remained, i've reset the pram also and no avail..

Ideas people?

edit: also tried swapping the ram out with my macbook and still didnt work

Thanks but I have been through and tried all the instructions in those guides

I forgot it had an old windows installation on it, and it just booted into that fine.. weird

Problem fixed, took it to Apple a week ago today, they told me they would charge a flat rate of $280 for labor, and whatever parts would need to be replaced.

Got it back on Friday, the logic board was replaced just like i thought it needed to be. They also replaced the bottom case (Sleep indicator light wasn't working), the top case (for cracking), and the display bezel (for cracking). They said it was a power issue with the Logic Board hmm..

Great service Apple, i looked up the price for the logic board and it was about $500 and they replaced mine and 3 other parts for half the price of just the board and it took less than a week.

MacRumors attracts a broad audience
of both consumers and professionals interested in
the latest technologies and products. We also boast an active community focused on
purchasing decisions and technical aspects of the iPhone, iPod, iPad, and Mac platforms.